Detect subsequence in linked list
Last updated: November 16, 2025
Quick Overview
Given a linked list and a sequence of integers, determine if the sequence is a subsequence of the linked list. You should return a boolean value indicating whether the subsequence exists within the linked list, maintaining the order of elements.
Twilio
November 16, 202510
6
1,996 solved
Given a linked list and a sequence of integers, determine if the sequence is a subsequence of the linked list. You should return a boolean value indicating whether the subsequence exists within the linked list, maintaining the order of elements.
Twilio uses this problem in the Onsite to evaluate your algorithmic thinking. They expect you to discuss multiple approaches, analyze trade-offs between them, and implement the optimal solution with clean, readable code.
What the Interviewer Expects
- Quickly identify the optimal approach and its theoretical basis
- Handle complex algorithm design with multiple interacting components
- Write concise, elegant code under time pressure
- Prove correctness of your approach and discuss alternative solutions
- Optimize beyond the obvious: discuss constant factor improvements
- Address follow-up variations and explain how the solution generalizes
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- What if the input doesn't fit in memory?
- How would you test this solution thoroughly?
- How would your solution change if the input was sorted?
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Practice DSA ProblemsSample Answer
Problem Analysis
To determine if a sequence of integers is a subsequence of a linked list, we can leverage the two-pointer technique. The essence of the problem is to traverse both the linked list and the input sequen...
Approach
- Initialize two pointers:
linked_list_ptrstarting at the head of the linked list andsequence_ptrstarting at the first element of the sequence. - Traverse the linked list:
- If the current...
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